Problems with my boyfriend's father?

Okay so i've been with my boyfriend for a while now, and its a serious relationship. He is always coming over, and hanging out with my family. My parents are interested in my boyfriend, and ask him interesting questions about his life, school, etc. So they have great conversations, and get along quite well! :) But i dread everytime I go to HIS house, because he has a father, and a stepmother, who don't talk to me... I'm a shy person when it comes to people who i DONT know :/ But if his parents would start the conversation, and ask me if i'm in any sports, or where i was born, or ANYTHING that would start a conversation, it would be easy. But his dad just doesn't seem to take an interest into talking to me, and he doesn't ask any questions. &one night when i was leaving his house, i said goodbye to him and thanked him for having me over, but he completely ignored me.. I don't know what to do. I've told my boyfriend that I don't think his dad likes me, but he tells me otherwise. And then my boyfriend gets upset with me that i dont talk to his family. Well I would if they would have something to sa, but his dad just always ignores me! What should i do??